Dairy cows give milk—and energy

Minnesota State Roundup

A Princeton, Minn., dairy farmer is using a new piece of equipment
called a digester to capture the methane in cow manure and turn
it into energy. The 450-cow herd produces about 1,700 gallons of
manure dailythat's enough gas to heat the barns and provide
electricity to 28 homes. In addition to capturing the methane for
power, the digester controls the odor produced by the manure gas.
The remaining manure turns into fertilizer for the cornfields that
feed the cows, thus bringing the process full circle.

About six digesters can be found in Minnesota, with another dozen
or so around the nation. The technology is not cheap: The cost of
Princeton farm's system was about $300,000, but would be less for
smaller farms.